The present invention relates to a secondary scanning control system for use in a facsmile equipment having a redundancy suppressing coding function.
Generally, facsmile equipment having a redundancy suppressing coding function are arranged so as to intermittently perform the secondary scanning (scanning in a direction relative to a recording or recorded paper sheet for recording or reading of image information) of the image reading or recording section so that the facsmile operation is matchable with the image information transmission, because the image information amount greatly varies in accordance with the contents of the original, to be transmitted, under the condition of a constant transmission speed. However, such an intermittent secondary scanning operation causes limitation to be imposed upon high-speed scanning and difficulty to be encountered to satisfy the follow-up of the mechanism such as a motor in the secondary scanning system, thereby resulting in deterioration of the image quality. One possible solution is to control the secondary scanning speed as exemplified by the Japanese Patent Publication No. 60-20950. That is, according to the prior art secondary scanning control system for facsimile equipment having a redundancy suppressing coding function, the image information amount stored in a line memory is periodically checked at every predetermined interval with respect to the secondary scanning speed so as to stepwise change, in accordance with the result, the secondary scanning speed for the next predetermined interval. There is a problem, however, in that it is required to increase the number of the steps of the secondary scanning speeds because the great speed variation easily affects the image particularly at the transition from the present interval to the next interval, while increasing the number of the steps of the secondary scanning speeds takes a long time in changing to a desirable scanning speed and the disturbance of the image tends to occur due to the frequent stepwise speed changing operation so that limitation is imposed upon the increase in the number of the steps of the scanning speeds. In addition, because the determination of the secondary scanning speed with respect to the image information amount is effected in units of line, the processing amount increases in response to the increase in the secondary scanning speed so as to impose a heavy burden upon the image information detecting section and the secondary scanning speed control section.